2 Proportions for Improve On-time Delivery

Use 2 Proportions to demonstrate that the proportion of on-time delivery increases after a process improvement.

This example applies to the Supply Chain Module. For more information, go to www.minitab.com/supply-chain-module.

Example

On-time delivery is the proportion of orders that arrive on schedule. To calculate on-time delivery rate, divide the total number of on-time deliveries by the total number of deliveries.

In this worksheet, On Time Before and On Time After represent the number of orders delivered on time before and after a process improvement. Total Orders Before and Total Orders After represent the total number of delivered orders before and after the process improvement.

With summarized data, you enter the data values instead of the column identifiers.

`On Time Before`	`Total Orders Before`	`On Time After`	`Total Orders After`
1053	1387	1132	1244

How-to

Choose Solutions Modules > Functions > Supply Chain KPIs, then select Launch.
Under Delivery, select On-time delivery.
Select Improve on-time delivery, then click OK.
Select 2 Proportions, then click OK.
From the drop-down list, select Summarized data.
In Number of events, enter the number of on-time deliveries before the process improvement as Sample 1. Enter the number of on-time deliveries after the process improvement as Sample 2.
In Number of trials, enter the total number of deliveries before the process improvement as Sample 1. Enter the total number of deliveries after the process improvement as Sample 2.
Select Options. In Alternative hypothesis, select Difference < hypothesized difference. The hypothesized difference defines your null hypothesis. By default, the hypothesized difference = 0. This one-sided test has greater power to detect whether the proportion of on-time deliveries increased after the process change.
Click OK.

Tip

For more information about this analysis, click Help in the main dialog box.